With the continuous development of science and technology, flat panel display (FPD) technologies such as liquid crystal display (LCD), plasma display panel (PDP) and organic light-emitting display (OLED) become increasingly mature, and display devices of a transparent display mode also begin to appear in people's vision. In the transparent display mode, users not only can see images displayed on panels but also can see objects at the rear of the display devices. The transparent display devices can be applied to windshields or household glass so as to provide information required by the users.
It has been noted, in realizing the transparent display mode, that the display mode requires the use of a special liquid crystal, i.e., cholesteric liquid crystal.
Cholesteric liquid crystal is composed of chiral liquid crystal molecules having periodic helical structure in arrangement. The liquid crystal molecules with helical structure have two stable textures: planar (P) texture and focal conical (FC) texture. Liquid crystals in the P texture can reflect the ambient light and hence can be used for forming a bright state while liquid crystals in the FC texture can transmit the ambient light and hence can be used for forming a dark state by light transmission. Therefore, the P texture and the FC texture of the cholesteric liquid crystals can form a pair of contrast states, thereby achieving the function of display.